The present invention relates broadly to the removal of oil, fuels, and other hydrocarbons or solvents from water, which may be fresh, salt, brackish, or other, and more particularly to an oil-sorbing filter cartridge or other type element such as for a bilge water treatment system for a watercraft.
Various systems are known for removing at least some of the oil and other hydrocarbons, which often is contained in bilge water before the water is pumped overboard or otherwise discharged. Such systems are described, for example, in commonly-assigned WO 02/062445, and in U.S. Pat. Nos. 4,031,839; 4,066,545; 4,058,463; and 6,056,881. Many of these systems utilize a cartridge-type or other filter element having an oil-sorbing or other medium for removing the oil from the discharge stream. Such filters and media therefor, as well as other filters and media for separating oil from water, may be further described in U.S. Pat. Nos. 3,847,821; 4,031,839; 4,359,386; 5,092,911; 6,143,172; 6,200,484; 6,344,519; 6,475,393; 6,485,639; and 6,503,390, in U.S. Publication No. 2002/0195384, and in the publication “Powerboat Reports,” March 2002, pp. 20-22.
Heretofore, many of such filters employed a fibrous or loose fill adsorbent medium such as polypropylene or other polymer, or activated carbon. It has been observed, however, that media of such type may not always perform optimally due to settling of the medium within the canister or other housing within which it may be contained, or due to channeling caused by the flow of the treatment stream. In either case, the service life of the filter may be prematurely shortened as the water being treated may bypass a majority of the media which may still be fresh. Accordingly, it is believed there remains a need for an improved oil-sorbing filter cartridge for use in bilge water treatment systems and in other fields similarly concerned such as for the treatment of waste streams from industrial processes.